Ivan
Eats Squid
The rumours of helmets causing neck injuries are probably just that...rumours. And, there are sites like these that propagate them
http://www.usff.com/hldl/
http://www.usff.com/hldl/
HELMETS OFTEN KILL RIDERS
Helmets Break Necks In At Least Three Ways:
1. The Hangman's Noose Analogy -- A case report by the Naval Safety Center introduced this analogy in the early 1970's in a report entitled "The Cervicocranium and the Aviator's Protective Helmet."
The report reads: "The inferior edge of the helmet, when visualized as part of the continuous circle completed by the nape strap and the chin strap, forms a loop that can be likened to a hangman's noose. The analogy might be further extended to include the lesions made about the neck by the straps or the edge of the helmet, paralleling the abrasions and contusions that might be associated with a rope having encircled the same structures. When the know is situated at the side of the head, such a hangman's noose produces fractures of the base of the skull, tending to extend bitemporally through the basisphoenoid."
Referencing a specific case, they continued, "One interesting and compelling aircraft accident investigated by the Naval Safety Center, Norfolk, Va., served to emphasize the practical application of their theoretical exercise. A Navy A-4 jet aircraft experienced difficulties in flight which caused the pilot to eject at an altitude, attitude, and air speed that were within the operating envelope of the ejection seat. Supported by a fully blossomed functioning parachute, however, the pilot reached the ground severely injured and died shortly after the accident, as a result of a transverse laceration of the cervical spinal cord."
"The details of the investigation established that the energy responsible for the fatal lesion was transmitted through the helmet and its inferior edge, into the neck. A vertebral dislocation resulted, which in turn severed the spinal cord."
This is undoubtedly what happened to McAfee. A blow to the side of the helmet, mild as it may have been, was just enough to have broken his neck and damaged his spinal cord sufficiently to have left him helplessly crippled. It is interesting to note that the very same type of impact was survived by Gary Bussy, who now claims that helmets save lives. It is interesting to consider that had Bussy been wearing a helmet when his head hit the curb, the combination of chin strap and helmet may have left him crippled for life, or even dead, rather than just mildly (relative to fatally) injured -- with only questionable brain damage as the end result.
2. The "Helmet Fulcrum" Scenario -- This study is another in Holt's bag of helmet facts.
In this study, the principles of engineering are studied as opposed to NHTSA's obsession with "head count" figures -- figures that will ultimately say whatever NHTSA wants them to say.
The "head count" method of evaluating helmet safety used primarily by NHTSA to support their standard has no place in the professional practice of safety engineering. There is no need for accidents to occur in order to establish foreseeability so that corrective action may be taken.
The "helmet fulcrum" investigation was initiated by preparing an illustrative drawing (Figure 2). An average man was drawn showing extension of the articular assembly, which constitutes the head-neck assembly. It can be seen that even in normal extension the helmet has met the cervical column at the third and forth vertical vertebrae and acts as a fulcrum to resist or oppose the force of translation of the head relative to the thorax.
This translation of the "helmet fulcrum" scenario means as force is applied to the front of the helmet and the head is forced back, the victims neck is either sheered severing the spinal cord and instantly killing the victim, or the spine is hyperextended and the chances of total paralysis and lingering death are certain in most instances.
In general, helmet design emphasis has been placed on cranial impact protection together with product appearance and cost factors -- particularly in relation to the FMVSS 218 standard which we have already described as being formed virtually by the Bell Helmet Company, and merely adopted to suit their needs by NHTSA's engineers.
No one we have contacted, especially Holt, has been able to confirm that this "helmet fulcrum" scenario has ever been considered, much less plausibly rejected, by the NHTSA safety engineers.
3. Damage To The Brain Stem From The Chin-bar On The Full-face Helmet -- This illustration (Figure 3) has been around for a while, almost long enough that one would think NHTSA would have seen it and done something about it by now -- if their concern were truly rider safety.
As the figure indicates, a blow to the chin-bar translates into yet one more way to hyperextend the spinal cord and bring about instant paralysis or death.
In most instances helmets used for sporting activities provide the use with cranial impact protection and have reduced injuries and associated deaths caused by these same helmets. A review of the maximum amplitude and velocity of movement of the head to thorax linkage for extension/hyperextension, as related to helmet design, revealed serious design deficiencies in helmets which readily comply with NHTSA's so-called safety standard. It is evident that protection should prevent injuries, not cause them, and protection of one part of the body at the expense of another is not an acceptable design philosophy. In other words, FMVSS 218 sucks!
When asked, "Will you guarantee that a helmet meeting these standards will protect a rider in a collision?" NHTSA will answer something along the lines of, "A helmet which passes our performance standards is considered in compliance with the provisions of FMVSS 218, and therefore in compliance with the law." and nothing more.
